﻿Shader "PostEffect/BugButGood"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
		_Angle("Angle", Float) = 0.0
		_MaskColor("MaskColor", Color) = (1,1,1,1)
		_IsForward("IsForward", Int) = 0
	}
	SubShader
	{
		// No culling or depth
		Cull Off ZWrite Off ZTest Always

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag

			#include "UnityCG.cginc"

			struct appdata
			{
				float4 vertex : POSITION;
				float2 uv : TEXCOORD0;
			};

			struct v2f
			{
				float2 uv : TEXCOORD0;
				float4 vertex : SV_POSITION;
			};

			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv = v.uv;
				return o;
			}

			sampler2D _MainTex;
			float _Angle;
			fixed4 _MaskColor;
			int _IsForward;

			float GetColor(float2 uv);
			float Gauss(float2 uv);

			fixed4 frag (v2f i) : SV_Target
			{
				fixed4 col = tex2D(_MainTex, i.uv);
				float a = Gauss(i.uv);
				col = 1 - (1 - a) * (1 - col);

				// float2 dir = i.uv - float2(0.5, 0.0);
				// float len = length(dir); //这里+1是把区间(0,maxlen)映射到(1,maxlen+1)，防止len过小的浮点误差
				// dir = normalize(dir);
				
				// if(len < 0.001f)
				// 	return 1 - 0 * col;

				// //做个模糊反走样
				// float threshold = 0.001f;	//模糊边界的阈值(单位为弧长)
				// float theta = acos(dot(dir, float2(1,0)));
				// float dtheta = theta - _Angle;
				// float arc = dtheta * len;
				// float r = 0.5 * (arc - threshold) / threshold;
				// r = max(r, 0); r = min(r, 1);   //r代表输出颜色中白色占的比例

				// //当IsForward=0，对r反向; 反之r不变
				// r = _IsForward * r + !_IsForward * (1 - r);

				// //输出颜色
				// col = 1 - r * (1 - col);

				return col;
			}

			//对GetColor采样的灰度图做模糊
			float Gauss(float2 uv)
			{
				float a = 0;
				//return GetColor(uv);
				
				a += GetColor(uv+float2(-1,1));
				a += 2 * GetColor(uv+float2(0,1));
				a += GetColor(uv+float2(1,1));
				
				a += 2 * GetColor(uv+float2(-1,0));
				a += 4 * GetColor(uv+float2(0,0));
				a += 2 *GetColor(uv+float2(1,0));
				
				a += GetColor(uv+float2(-1,-1));
				a += 2 * GetColor(uv+float2(0,-1));
				a += GetColor(uv+float2(1,-1));

				a = a / 16;

				return a;
			}	

			//采样灰度
			float GetColor(float2 uv)
			{
				float2 dir = normalize(uv - float2(0.5, 0.0));
				
				int r = step(cos(_Angle), dot(dir, float2(1, 0)));
				r = _IsForward * r + !_IsForward * !r;

				return r;
			}


			ENDCG
		}
	}
}
